CDC raises estimates of H1N1 toll slightly

Apr 20, 2010 (CIDRAP News) – The US Centers for Disease Control and Prevention (CDC) yesterday updated its estimates for the number of pandemic H1N1 illnesses, hospitalizations, and deaths, adding another month of data and bumping up the totals slightly.

From April 2009 to Mar 13 of this year, the CDC estimates about 60 million people were infected with the pandemic H1N1 virus, about 270,000 were hospitalized, and about 12,270 died.

The totals reflect small increases in disease burden that are in line with very low levels of flu activity across most parts of the nation for the past several weeks. The new estimates add 1 million more infections, 5,000 more hospitalizations, and 270 more fatalities to the total since the agency's Mar 12 update.

Continuing a pattern seen throughout the pandemic, the CDC's numbers show that the flu is exacting the greatest toll on younger age groups. It estimated 19 million cases occurred in children though age 17, representing about 25.7 % of this age-group, leading to 86,000 hospitalizations and 1,270 deaths. For adults ages 18 through 64 the estimate is 35 million cases, representing about 18.5% of this population, with 158,000 hospitalizations and 9,420 deaths.

The new estimates for people ages 65 or older—who are thought to have some protection because of past flu exposures—rose to 6 million cases, about 15.8% of the population, with hospitalizations rising to 26,000 and deaths to 1,580. In the CDC's last estimate, the percentage of older people infected with the virus was put at 13%.

All the numbers represent the midpoints of ranges of estimates the CDC produced with a new estimation method that it unveiled in November. Estimating the true burden is difficult, because many people who have the flu don't seek care, and only a few who see their doctors are tested for the virus. The CDC has said the number of confirmed cases greatly undercounts the true number of infections.